Advances in Sample Preparation最新文献

Some of the challenges to developing greener sample preparation procedures are related to finding solvents and practices with low environmental impacts. Given the importance of CO₂, water, and ethanol compared to other green solvents in flavonoid extractions, it is convenient to explore changes in how they are employed. Depending on temperature and pressure, these three solvents may present total or partial miscibility that can be used conveniently in sample preparation. In this work, the Lippia origanoides (Verbenaceae family) vegetal material remnant after essential oil distillation was extracted with either aqueous ethanol (EtOH), ethanol-modified supercritical CO₂ (EtOHCO₂), or two coexisting CO₂ fluid phases [(CO₂)²]. The latter was the extractive practice that afforded higher selectivity and yield of pinocembrin (Pn) and galangin (Gn), two important active ingredients for pharmaceutical applications. EtOH extraction was the practice with the highest whole yield, and its extract contained mainly glycosylated compounds, in contrast to those extraction systems that involved CO₂. The presence of CO₂ allowed selective extraction of nonglycosylated flavonoids, possibly due to π−π intermolecular interactions with them. Flavonoids whose B-ring is a benzene or phenol group were recovered in higher amount. By means of the EtOHCO₂ and (CO₂)² techniques, the extraction/isolation of Pn and Gn was achieved with less ethanol consumption and lower environmental impacts. The best setup was extraction with (CO₂)² and isolation by preparative HPLC. These results are promising for increasing selectivity and yield in some specific sample preparations.

The treatment of biological samples, especially from complex matrices, has consistently challenged analytical operators. The classic problems to be faced for any analysis, regardless of the origin of the sample, such as for example contamination and loss of analyte, in biological samples, are particularly emphasized. In particular, the main cause of the error is due to the degradation of the analyte which in several cases due to biological interaction. Many factors can influence the stability of drugs, chief among them the physicochemical properties of the drug, characteristics of the matrix, the tendency to conjugation/deconjugation, sample collection procedure, container characteristics (e.g., oxidation, adsorption), and the use of preservatives or other additives. The problem is severe in the toxicological and forensic fields, especially for analyzes considered "non-repeatable." In this review, we will explore all the major problems in the pre-extraction phase for the chemical-analytical aspect in the pharmacotoxicological and forensic fields.

In this work, the characterization of several reversed-phase and HILIC chromatographic systems is presented by means of the Abraham's solvation parameter model, focusing on the impact of solute polarizability, dipolarity, hydrogen bonding, and molecular volume on chromatographic retention. Although retention times in octadecylsilane columns are clearly dependent on the nature and content of the organic modifier in the mobile phase, similar chromatographic selectivities are reported for eluents containing acetonitrile or methanol in the range between 40 and 80%. The most relevant analyte properties affecting retention are the hydrogen bond acceptor capacity and the molecular volume, the former favoring partition into the mobile phase and the latter into the stationary phase. The behavior of HILIC systems greatly depends on the nature of the support (silica or polymeric), the bonded phase (zwitterionic, aminopropyl, dihydroxypropyl) and the organic solvent used in the eluent (acetonitrile or methanol), but they have in common that larger solute volumes allow more favorable partition into the organic solvent-rich mobile phase. The evaluation of the chromatographic retention of ionized analytes in HILIC should be performed with care, since they may interact with ionized buffering species, leading to unexpected lower retentions.

Natural extracts of bee products are being recognized worldwide as a remarkable source of bioactive compounds with diverse functionalities such as antioxidant, antimicrobial and anticancer agents. Some of these compounds are used in the pharmaceutical area and for the development of new functional foods with the aim of improving the bioactivity of current food products, their properties, and replacing other synthetic components. Conventional extraction methods such as maceration, magnetic stirring, or soxhlet mainly involve the use of toxic solvents in large quantities and long extraction times, among many other drawbacks. For this reason, the latest generation of chemical technology is committed to clean and environmentally friendly technologies by applying green analytical chemistry. This new approach defines the use of chemistry for pollution prevention, i.e. the design of methods and processes that reduce or eliminate the use and generation of toxic or hazardous substances. Recently, green sample preparation methods (ultrasound assisted extraction, microwave assisted extraction, pressurized fluid extraction or QuEChERS) have been proposed and successfully applied for the extraction of bioactive compounds from bee products, mainly propolis, bee pollen and honey. This has been achieved by significantly minimizing the impact on environment, by reducing the use of organic solvents, using green solvents, reducing extraction time as well as extra steps. These new alternative methodologies have aroused the interest of researchers as future application prospects with high yields for the recovery of bioactive compounds. This review provides a comprehensive and up-to-date overview of green sample preparation methods for the extraction of bioactive compounds from bee products.

The idea of Green Chemistry began to take shape in an increasingly important way starting in the 90 s when the impact of chemical products and processes began to be critically evaluated.

In the analytical chemistry field, green chemistry represents an essential factor to consider whenever a laboratory procedure is planned. Therefore, from the start it is necessary examine not only green chemistry (GC) but also green analytical chemistry (GAC). The impact of the GAC on publications shows how the trend has seen an exponential increase from 1995 to 2018. From here, it is evident how the GAC is increasingly essential in the analytical chemist work who needs uniform, impartial, and standardized tools and elements to evaluate the "green profile" of the procedures, also in order to perform a direct comparison between methods and procedures.

The purpose of this review is to report, compare, and critically evaluate the tools available today, such as Life Cycle Assessment (LCA), National Environmental Methods Index (NEMI), Analytical Eco-Scale, Green Analytical Procedure Index (GAPI) and ComplexGAPI, RGB (Red Green Blue) and White Analytical Chemistry (WAC) models, hexagon-CALIFICAMET, and finally Analytical GREEnness Metric approach (AGREE) and AGREEprep. This comparison was performed in the text after a short introduction to the concepts and principles related explicitly to GC, GAC, and Green Sample Preparation (GSP).

The extraction of non-volatile and semi-volatile analytes from solid and semisolid samples has been primarily carried out via heated and/or pressurized liquid extraction mechanisms. Although analyte extraction and concentration processes have significantly evolved and currently several automated solutions are commercially available, these two steps are carried out independently. To the best of our knowledge, human intervention is always required throughout the entire process for sample extract manipulation/transportation among instruments/processes. Expectedly, excessive sample handling throughout the analytical workflow contributes to an increase in the analysis cost, the loss of analyte (s), and numerous potential analytical errors. Herein, we present the first fully automated sample-to-vial solution for analysis of non-volatile and semi-volatile compounds from solid and semisolid samples. This technological development, which is based on gas assisted dynamic accelerated solvent extraction (GA-dASE) and an integrated level-sensing system that controls the endpoint of the evaporation step, allows for fully automated analyte extraction and analyte enrichment. As a proof of concept, we applied this fully automatic extraction and enrichment system towards the quantitative determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in soil samples. Our results showed that GA-dASE not only matched the performance of the legacy accelerated solvent extraction (ASE), in terms of analyte recovery and reproducibility, but also delivered nearly 3-time reduction in labor per sample. Furthermore, our experiments demonstrated the capability of the instrument to perform fully automated extraction and evaporation steps without human intervention and with no impact on data quality (Relative Standard Deviation, RSD, ≤ 20%). In terms of interlaboratory reproducibility (n = 2), our results showed comparable results for the determination of PAHs using either 10- or 100-mL sample cells.

Inorganic arsenic is considered one of the most critical and severe environmental problems due to its high toxicity even at low levels of exposure, causing serious health problems. Humans can be exposed to arsenic mainly through inhalation, ingestion of food and water, especially in certain areas where water comes into contact with arsenic-bearing minerals. For natural geological reasons, water in some areas of the world may contain more arsenic than usual. For these circumstances, the development of methods for the removal of arsenic from water has been of increasing interest in recent years. This work presents an optimised removal of As(III) and As(V) from water by the in situ formation of ferrite (Fe₃O₄) nanoparticles, leading to the adsorption of this element in the Fe₃O₄ structure. In addition, the magnetic properties of the nanoparticles facilitate their removal from the medium by a magnet. The experimental conditions of the process were optimised and the total removal of high concentrations of As(III) and As(V) in water was achieved in only two minutes and at 50 °C at basic pH, using 200 µL of a 0.2 M FeCl₂·4H₂O solution and 100 µL of a 0.1 M FeCl₃·6H₂O solution to form Fe₃O₄ in situ. The ferrite surface was characterised by field emission scanning electron microscopy before and after the arsenic removal process and by energy dispersive X-ray spectroscopy before the process. The study of adsorption kinetics and equilibrium isotherms reveals a Langmuir-type physicochemical process.

Green Chemistry can be defined as the design of processes that reduce or eliminate hazardous substances and are described by the 12 Principles of Green Chemistry (PGCs). The PGCs provides a guide of the green characteristics that a chemical process should fulfill. However, the evaluation is complicated without an adequate metric that provides the possibility to convert the characteristics of the method to an objective scale level, such as a number or a color. For this purpose, green metrics have been developed in order to do a comprehensive evaluation of the method greenness. The older systems were based on atomic efficiency or mass of generated waste, but those are not adequate for all the chemistry branches, especially on Analytical Chemistry. Hence, a series of novel metrics, such as National Environmental Methods Index, Eco-Scale, Green Analytical Procedure Index, RGB model, Hexagon or Analytical GREEnness metric approach has appeared. Regarding Analytical Chemistry, especially in the sample preparation field, a novel trend based on the use of 3D printing devices has emerged. The different 3D printing modes offer the possibility to prepare devoted devices that affects the miniaturization, automation, reduction of solvents and can be prepared in short times with low energy. Therefore, 3D printing could offer novel alternatives in the preparation of Green Analytical Chemistry methods. In this work, the six mentioned metrics were used to evaluate the greenness of 11 published works that perform sample preparation using 3D printed devices. The results of each metric have been discussed and a comparison of all metrics has been done. The most adequate methodology for the evaluation was the Analytical GREEnness metric approach which was used to compare the greenness level of one of the selected works with a work using more conventional materials and systems. These results demonstrate the capabilities of 3D printing to help in the development of novel Green Analytical Chemistry methods.

A procedure for the determination of N,N-dipropyltryptamine, 5‑methoxy-N,N-dimethyltryptamine, and 5‑methoxy-N-methyl-N-isopropyltryptamine in urine has been developed based on a microextraction by packed sorbent (MEPS) followed by ion mobility spectrometry determination. The combination of microextraction by packed sorbent with ion mobility spectrometry provided promising advantages for in-field screening of new psychoactive substances in urine, due to its simplicity, automation, and portability. The effect of sample pH and ionic strength, and the number of loading and elution steps has been evaluated. The obtained limits of quantification ranged from 21 to 29 µg L⁻¹, and accuracy and precision were evaluated by the determination of blank urine samples spiked at limits of quantification, 250, and 500 µg L⁻¹ synthetic tryptamines, with recovery values in the range of 76–95% and relative standard deviations lower than 20%. Moreover, the environmental impact and greenness of the proposed extraction method has been evaluated, providing an AGREEprep score of 0.62. Thus, the developed methodology can be considered a reliable and green screening methodology for in-field abuse drug consumption detection.